The present disclosure relates to digital imaging and particularly in devices employed for scanning, copying and printing in enterprise or office environments where the user can input a document either as a printed sheet or an electronically created document such as from a desktop computer into a multi-function device for effecting scanning, copying and printing as the case may be. Heretofore, the technique of dynamic range adjustment of the image has been performed for image compression and the purpose of background suppression; however, this can result in changing of the colors of the image in the case of a colored document thereby producing undesired shifts in the appearance of the image. The linear transformation employed for image compression and background suppression has utilized a gain change and an offset based upon a mapping of the pixel content distribution in the image. This technique has provided image compression and background suppression but as mentioned before, has not been altogether satisfactory when applied to color images.
Thus, it has been desired to provide a way or means of image compression and background suppression of digital imaging in any manner which can provide desired contrast changes and background suppression without distorting the colors or overall appearance of the image.